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12 volt battery does not seem to be charging correctly.

Discussion in 'Gen 4 Prius Main Forum' started by Ozark Man, Jun 1, 2021.

  1. RGeB

    RGeB Member

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    Thanks alanclarkeau and Tideland Prius. What a shame that the tis site (techinfo.toyota) has no real technical detail. For example, my understanding is that it gives car owners (who pay the extra to become subscribers) no details on how (ie the algorithms by which) specific 'battery condition' and 'electric load' parameters are used to calculate the voltage requested from the DC-DC converter. This kind of technical detail would be really interesting to know, at least for technically interested owners. As I have griped before, all of the relevant 12v battery charging parameters can be programmed by the owner of a $150 smart charger, but they can not be known (let alone programmed) by the owner of a $40,000 Toyota hybrid car. Anyhow, Alan's post is a start; very interesting to compare it with details that other manufacturers do provide to owners; and with an owner's own measurements of course.
     
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  2. jerrymildred

    jerrymildred Senior Member

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    I'd like the recipe for KFC chicken. :D If you think car owners are interested, imagine how interested the competing car makers might be. Why develop anything yourself when you can just use someone else's inventions like the Chinese do? I'm pretty sure Toyota's philosophy is to let them figure it out for themselves or else pay royalties. It's the difference between free and open source software and commercial software.

    However, there's a chance the algorithms might be patented, in which case you might learn something by rooting through the files in the patent office. I can't imagine that would be worth it, though. ;)
     
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  3. FuelMiser

    FuelMiser Senior Member

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    Gen 4's use a different battery spec than Gen 2 or 3. Different chemistry and form factor. Oh, and different location. It's now under the hood.
     
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  4. ChapmanF

    ChapmanF Senior Member

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    patents.google.com makes that kind of rooting really easy to do from wherever you are, and yes, you can learn pretty interesting things.
     
  5. RGeB

    RGeB Member

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    If anyone knows the postulated patent #s, I would be interested to read them. But I suspect that Toyota relies on 'trade secrets' rather than patents in such cases (even if the algorithms met the requirements for patent protection, which probably they do not). Remember, patented information becomes free for public use after about 20 years. Supposed 'trade secrets' can be used forever as an excuse not to reveal information to which owners ought to be entitled.

    Having already paid for the car (not rented it from Toyota), the owner is entitled to know how optimally to use the car they have purchased. For example, many people think that Toyota 12v battery charging algorithms are sub-optimal. Some people think that these algorithms may be designed to help Toyota meet some market nation's emission control rules, rather than optimize the battery life experienced by an owner. We can not know, as the algorithms are not revealed by Toyota to owners.

    Many owners of Toyota and other cars have observed that battery life can be substantially improved by weekly topping up using a smart charger. (The smart charger manufacturers reveal how optimally to use the device they sell, rather than hide this vital and valid information from owners). The details depend on circumstances of individual car owners (driving patterns etc). Lead-acid batteries are adversely affected (by known mechanisms) by prolonged under-charging, so this observation is consistent with the speculation above. But it remains speculation, because the algorithms are not revealed by Toyota to owners.

    As to 'double guessing' a car 'brain', any sheep-dog has a brain capable of computations far more complex than any car computer. But even a sheep-dog needs to be trained to achieve optimal performance in particular circumstances. There are many 'secrets' about sheep-dog brain function, but humans have learned how to train sheep-dogs. Car computer algorithms are programmed by humans. The programming may not be optimal for all owners. But this 'training' is very difficult to improve, as the 'trained settings' are not revealed by Toyota to owners (let alone adjustable by owners).

    Car owners can be enabled to make valid adjustments, without compromising valid secrets about car manufacture.

    End of extended gripe. You can probably tell that my first car was a 1963 VW beetle with a shiny black generator box on the engine, and a mechanic or technically capable owner could adjust output to the battery. It was not a great system, but at least it was not secret. Toyota hybrids are great cars (much better than '63 beetles). They would be even better, with more credit to Toyota, if owners could more easily obtain technical details (and, if appropriate, arrange programming that suited their circumstances) about the 12v charging system.
     
  6. ChapmanF

    ChapmanF Senior Member

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    Yay! Your Prius transmission is pretty recognizably John Godfrey Parry Thomas's idea from 1908. :)

    In that case, of course, it wasn't the 20 year patent protection that slowed things down; it took much longer than that to have computers fast enough to make anything like the Prius's real-time control of the thing practical.

    Toyota might use a combination of trade-secret and patent protection ... I think they do file a fair number of patents.
     
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  7. sam spade 2

    sam spade 2 Senior Member

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    Given the world population these days, you can find "many people" who "think" almost anything that your imagination can conjure up.
    That doesn't make it right. Or even close in most cases.

    Most ANY modern car that sits more than it is driven is prone to early battery failure.
    And that possibility can be minimized by periodically manually charging. Even with a riding lawn mower.
    People who buy hybrids might be more prone to drive less.

    It is called "Jumping to conclusions"......that often are unwarranted.
     
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  8. alanclarkeau

    alanclarkeau Senior Member

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    And - some of the processes they can change by a plug-in to the workshop computer - my FIESTA Diesel, when I took home from 30,000 km service was driving quite differently - so much so that I rang them. They told me that it'd had a re-flash of the xyz processor with a number of improvements - that happened a few times with my FORDs. So what is in the specs might change.

    Back in the '70s, I had a VOLVO 164E with (I think) D-Jetronic Electronic Fuel injection - couldn't find any data about it - I did get a Schematic diagram only. As for VOLVO's proprietary changes to BOSCH's design - even VOLVO service didn't have a clue - it was "send it away and get it fixed". Not that it ever played up, but I was "interested". Great car though.
     
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  9. BellevilleMXZ

    BellevilleMXZ Member

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    They are not going to have it so you can tweak charging.(or most things) on any car...first off, someone would get poking around and screw it up....then blame Toyota(or any other manu.). Secondly 99%of people wouldn't understand or be interested to know about it. Third, its not a set algorithm , and I'm sure its different to some degree on every model and year, and maybe even trim level. And if they come out with a software update( which is VERY common these days, even multiple updates on one particular ECM) then all those , or just a few....parameters can change. Four, newer cars are much more apt to drain a battery if sitting for any length of time, there is alot of stuff to keep alive .I see more dead batts on the lot than ever before. And no manu.releases much in depth info of how stuff works, even to dealer techs. When we go to any Chrysler training, they go into a fair bit of detail, but not what you are looking for, on any system. Its just not needed. I get where u are coming from, and you sound like a sharp guy.....but most people are not, and shouldn't be poking around "adjusting" things.
     
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  10. Michael Wood

    Michael Wood Active Member

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    I'm conducting an experiment using both my Prii (2015 and 2020). I bring the aux batteries up to green float charge using a Deltran Battery Tender Plus, at least once every 2 weeks, when parked over the weekend. By the end of next year I'll know whether or not this practice adds any value in terms of 12v longevity.
     
  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Our 2010 has an Optima Yellow Top, installed in Sept of 2015. It's garage parked, and we're doing at most 4K kms per year the last few years. When idle, which is most days, it's always connected to a CTEK 4.3 charger (quick-connect wiring harness and garage storage makes this easy), and still shows as-new stats when assessed with a Solar BA5 tester.
     
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